(1) Field of the Invention
The present invention relates to an improved fastener assembly which is particularly useful for assembling a rocker arm cover to an engine block. In particular, the present invention relates to a three piece fastener assembly comprised of a bolt having a head and a partially threaded shaft that is mounted for axial movement inside of a rubber-like or elastic grommet with an intermediate washer secured to the grommet adjacent to the bolt head. The washer engages a stop means on a lower portion of the bolt between the head and the threaded end, to prevent removal of the bolt from the grommet and washer. During assembly, the fastener assembly is positioned in an opening in the rocker arm cover or the like with the bolt in a raised position so that it does not interfere with the alignment of the rocker arm cover on the engine block. The stop means keep the bolt from slideably releasing from the grommet and the washer while the bolt is in the raised position. Arrow tabs project from the grommet and lock under the rocker arm cover to retain the fastener assembly in the rocker arm cover opening or the like. After the rocker arm cover is aligned on the engine block, the bolt is threadingly mated with a threaded aperture in the block, the extent of which is controlled by an annular shoulder portion of an unthreaded section of the shaft of the bolt. When the bolt is threaded into the engine block, the grommet is compressed somewhat by the washer and serves to both muffle noise that is generated in the engine block and to prevent moisture and fluid from leaking into or out of the engine block.
(2) Prior Art
The prior art has described various types of screw fastener assemblies comprised of a bolt and a washer member for securing a first workpiece to a second workpiece. Most of the prior art devices are designed to seal a washer member mounted on an expandable and flexible gasket against a workpiece so that when a fastener member is tightened against the washer, the gasket is not deformed to the extent that the gasket no longer provides an effective means for sealing out moisture and liquid from the opening in the workpiece through which the fastener has been secured. Other devices provide for axial play between a fastening bolt and a washer, but have more parts and are more complicated than the present invention. These fastener assemblies are more expensive to manufacture and since fastener assemblies are manufactured by the millions, a reduction in manufacturing costs of a few cents translates into a substantial yearly savings. Illustrative of the prior art fastener devices are U.S. Pat. Nos. 3,126,935 to Tuozzo; 3,202,022 to Weidner, Jr.; 3,286,577 to Weidner, Jr.; 3,422,721 to Yonkers; 3,670,618 to Jellison; 4,292,876 to De Graan; 4,521,147 to King, Jr. et al; 4,732,519 to Wagner and British Patent No. 2,601,560 to McKee, Jr.
Tuozzo describes a retractable screw fastener having a stand-off bushing, a threaded fastener and a resilient gasket. The stand-off is assembled to one of two workpieces being joined by the use of a flaring tool. The threaded fastener is formed essentially in the shape of a bolt with a head at one end of a shaft and a threaded section at the other end. The threaded section is larger than the shaft so that when the threaded section is inserted into the resilient gasket, the fastener slides through an opening in the gasket, but is not able to slide back out. The shaft is free to slide inside the washer so that when the washer is inserted into the stand-off opposite the flared end, the shaft of the fastener is slid down the gasket and the threaded end is threadably mated to an aperture in the other of the two parts to be joined. This is a complex fastener assembly and requires more handling of the workpieces to be joined than in the present invention.
Weidner, Jr. describes two types of fastener assemblies. U.S. Pat. No. 3,202,033 describes a bonded washer having a backing member secured to a sealing member. The washer has a shoulder that is provided to control the driving and sealing action of the washer. U.S. Pat. No. 3,286,577 provides a stiff backing sealing member and a resilient sealing member which overcomes the problem of the sealing member flowing away from the opening in the first workpiece being joined to the second workpiece. Neither of the Weidner, Jr. fastener devices allow for axial play between a fastening bolt and the washer which are mounted together.
Yonkers describes a washer like member which provides for self-aligning and sealing of a bolt and nut or a similar fastening device. The member comprises an arcuate washer having a ring-shaped plastic filler joined to the concave side thereof which defines a generally convex arcuate outer surface for sealing on a workpiece and having a longitudinal axis without the bolt or nut being perpendicular to a plane defining the face of the workpiece. The washer is not secured to the bolt prior to mounting.
Jellison describes a composite washer having a dome-shaped metal member and a resilient member such as neoprene bonded to the metal member. The resilient member comprises two components, the first of which is bonded to the metal member along its bottom surface at the high portion of the dome and substantially adjacent a central opening. The second component is positioned in a partially overlapping relationship with the first component and is also bonded to the metal member along the bottom surface, radially removed from the washers central opening. The metal member is shaped to restrict the resilient member from moving radially outward and to urge a radially inward movement. The bolt is not secured to the washer prior to fastening.
De Graan describes an improved steel and neoprene bonded washer having a crowned steel washer with an inner elastomeric washer. The elastomeric washer is adjacent to the concave surface of the crowned washer. The steel washer has a generally flat outer ring and a conical portion extending from the outer ring toward the central opening. The angle of the sides of the conical portion is between 30.degree. and 50.degree. with respect to the flat portion. The bolt is not secured to the washer prior to fastening.
King, Jr. et al describes a blind fastener including an outer sleeve member, a stem, an inner sleeve member and a deformable washer which fits between the inner and outer sleeve members. The inner sleeve member is driven into the outer sleeve member from the accessible side of two workpieces while being supported on the stem so as to radially expand the outer sleeve member into interference fit with the hole. The deformable washer is placed between the head flanges on the inner and outer sleeve members and is sized so that the washer is deformed to expand the countersunk head flange on the outer sleeve member into interference fit with the countersink in the workpieces during the final driving movement of the inner sleeve member. After the inner sleeve member is driven into the outer sleeve member, the stem is pulled from the accessible side of the workpieces to form the blind head on the outer sleeve member on the blind side of the workpieces. The blind head former on the stem provides for grip adjustment by wire drawing or similar grip adjustment techniques normally used for blind fasteners so that the breakneck groove in the stem can be lined up with the head on sleeve member to allow the stem to be separated flush with the head. Because of the interference fit, locking grooves on the stem engage the inner sleeve member to mechanically lock the stem in position in the sleeve members. The bolt is not secured to the washer prior to fastening.
British Patent No. 892,870 to McKee, Jr. describes a fastener for securing corrugated and other forms of sheeting to the surface of building structures. Sealing washers are mounted on the washers and prevent moisture from entering through openings in the sheeting and the adjacent building structure member through which the shank of the fastener passes. The bolt is not secured by a metal washer to the fastener and the bolt is not axially moveable.
Wagner describes a fastener assembly that is adapted for use in connection with a first and a second apertured workpiece. The bolt is axially moveable in a washer but is designed to hold the bolt and washer together. The Wagner fastener assembly comprises a fastener, a washer and a rubber grommet. The washer has a depending sleeve portion on which the grommet is radially mounted. The fastener has a head and a shank with the shank having an intermediate unthreaded portion, a distal threaded portion and a pair of discrete protuberances or wings spaced apart on the unthreaded shank portion adjacent to the distal threaded shank portion for limiting the axial movement of the fastener along an opening through the sleeve portion of the washer. The sleeve also serves to limit the amount of torque that can be applied to the threaded shank portion when the fastener is used to join the two workpieces. The use of a sleeved washer as the torque limiting element and the use of annular wings on the unthreaded shank portion as the axial limiting element for the fastener in the sleeved washer, increases the cost of manufacturing the Wagner fastener assembly as compared to the present invention.